1. Field of the Invention
This invention relates to a fire and/or explosion suppression system for process equipment wherein a pneumatic transport stream contains suspended potentially combustible material which is removed before the air is discharged to the atmosphere, but presents a fire or explosion hazard until such removal has been accomplished.
Low strength containment and process vessels used in dust collectors, process equipment, dryers, ovens, mills, bucket elevators, storage bins, hoppers, and similar devices are subject to catastrophic destruction if a fire and/or explosion occurs in the vessel, or enclosure, or adjacent conveying ducts or pipes, or associated processing units.
It is desirable though to avoid activation of fire and/or explosion suppression or isolation equipment unless there is verification of the occurrence of an untoward event.
In certain instances, there is a requirement that a blower forcing air through the containment enclosure be turned off as a means to stop further progress of a fire or explosion before release of a suppressant is effective because many times a fire will diminish as soon as the air flow is significantly reduced.
2. Description of the Prior Art
U.S. Pat. No. 4,637,473 discloses a fire suppression system for containment vessels wherein thermocouple temperature sensors are located at the inlet and outlet respectively of the vessel in order to sense a temperature differential therebetween. When a predetermined temperature difference occurs between the temperature of air at the inlet as compared to the air temperature at the outlet of the vessel, the blower fan is turned off. Another temperature sensor inside of the vessel controls release of a suppressant medium into the interior of the vessel.
Although the protection system of the '473 patent is useful in certain instances, normal fluctuations from time to time of the temperature of the air directed to the processing vessel detract from the overall reliability of the design. In certain instances, the sensors are unable to adequately react to temperature differentials throughout the entire temperature operating range to which the system is subjected.